1. Field of the Invention
The present invention relates to a caliper assembly for a disc brake of a vehicle and more particularly, to an improved caliper assembly including two pairs of operating rooms and a piston disposed within each operating room whereby hydraulic fluid pressure from a master cylinder presses the pistons, and the pistons press the peripheral edge surfaces of the pad plates so as to substantially eliminate noise and highly increase braking efficiency of the caliper assembly.
2. Description of Related Art
Various types of caliper assemblies are known in the art. Generally, a disc brake provides a braking function by pressing the disc with a pair of fluid pressurized pads. The disc brake has a number of advantages such as excellent heat radiation due to exposure thereof, and only a minimal loss of braking efficiency due to thermotransformation of the pads.
However, the caliper assembly for a disc brake does not prevent a squealing noise at the time of braking since a pad plate of a pad plate assembly is not tightly or permanently attached to the disc brake carrier, and therefore never successfully applies a powerful pushing force to the pads.
A conventional caliper assembly is described in Japanese Laid Open Utility Model Publication No. 50-141084, which includes a circular plate, a piston, a pad having a concave portion, and a pad plate having a convex portion slidably mounted to the concave portion of a pad for tightly contacting the pad to the pad plate. However, movement and thus noise or squealing will occur between the pad plate and the carrier, such that conventional caliper assemblies cannot reduce noise and cannot expect to improve a braking efficiency thereof.
As shown in FIG. 1, a conventional caliper assembly 50 includes a body 52 and a carrier member 66 slidably connected to the body 52 through a sliding bolt (not shown). The body 52 includes a cylinder 56, a piston 54 slidably disposed within the cylinder 56, and an annular seal 62 disposed around the circumference of the piston 54 for forming a seal between the interior wall of the cylinder 56 and the outer circumference of the piston 54.
A disc 64 is disposed between the carrier 66 and the piston 54 and is provided with a pair of right and left pads 60 and 61 disposed at opposing outer sides of the disc 64. Each pad 60 and 61 is fixed to a corresponding pad plate 58, 59. The pad plates 58, 59 are slidably retained on the carrier 66.
When fluid pressure operates to push the piston 54 in the cylinder 56 with fluid pressure from a master cylinder (not shown), the piston 54 moves to press the pad plate 58 and the right pad 60. At this time, the right pad 60 automatically presses the disc 64 and the left pad 61 simultaneously presses the disc 64 from the opposing side.
When the fluid pressure of the master cylinder is removed, the piston 54 returns to the original position and the pad plate 58 and right pad 60 separate from the disc 64 and the left pad 61 simultaneously separates from the disc 64.
However, such a conventional caliper assembly suffers from a number of problems. For example, the right and left pads 60 and 61 abrade unevenly since there is a space X between the piston 54 and the pad plate 58, therefore the pads 60 and 61 do not return to their original position. As a result, the pads 60 and 61 can be thermotransformed, thereby changing the properties thereof and potentially decreasing braking efficiency.